From 62aca403657fe30e5235c5331e9871e676d9ea0a Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 5 Mar 2012 14:59:19 -0800 Subject: alpha: fix 32/64-bit bug in futex support Michael Cree said: : : I have noticed some user space problems (pulseaudio crashes in pthread : : code, glibc/nptl test suite failures, java compiler freezes on SMP alpha : : systems) that arise when using a 2.6.39 or later kernel on Alpha. : : Bisecting between 2.6.38 and 2.6.39 (using glibc/nptl test suite as : : criterion for good/bad kernel) eventually leads to: : : : : 8d7718aa082aaf30a0b4989e1f04858952f941bc is the first bad commit : : commit 8d7718aa082aaf30a0b4989e1f04858952f941bc : : Author: Michel Lespinasse : : Date: Thu Mar 10 18:50:58 2011 -0800 : : : : futex: Sanitize futex ops argument types : : : : Change futex_atomic_op_inuser and futex_atomic_cmpxchg_inatomic : : prototypes to use u32 types for the futex as this is the data type the : : futex core code uses all over the place. : : : : Looking at the commit I see there is a change of the uaddr argument in : : the Alpha architecture specific code for futexes from int to u32, but I : : don't see why this should cause a problem. Richard Henderson said: : futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, : u32 oldval, u32 newval) : ... : : "r"(uaddr), "r"((long)oldval), "r"(newval) : : : There is no 32-bit compare instruction. These are implemented by : consistently extending the values to a 64-bit type. Since the : load instruction sign-extends, we want to sign-extend the other : quantity as well (despite the fact it's logically unsigned). : : So: : : - : "r"(uaddr), "r"((long)oldval), "r"(newval) : + : "r"(uaddr), "r"((long)(int)oldval), "r"(newval) : : should do the trick. Michael said: : This fixes the glibc test suite failures and the pulseaudio related : crashes, but it does not fix the java compiiler lockups that I was (and : are still) observing. That is some other problem. Reported-by: Michael Cree Tested-by: Michael Cree Acked-by: Phil Carmody Cc: Richard Henderson Cc: Michel Lespinasse Cc: Ivan Kokshaysky Reviewed-by: Matt Turner Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/alpha/include/asm/futex.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/alpha/include/asm') diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h index e8a761aee088..f939794363ac 100644 --- a/arch/alpha/include/asm/futex.h +++ b/arch/alpha/include/asm/futex.h @@ -108,7 +108,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, " lda $31,3b-2b(%0)\n" " .previous\n" : "+r"(ret), "=&r"(prev), "=&r"(cmp) - : "r"(uaddr), "r"((long)oldval), "r"(newval) + : "r"(uaddr), "r"((long)(int)oldval), "r"(newval) : "memory"); *uval = prev; -- cgit v1.2.3